1. Field of the Invention
The present invention relates to an optical assembly, and more particularly to an optical assembly combined by an adhesive.
2. Description of Related Art
FIG. 1A illustrates a schematic cross-sectional view of an adhesive optical assembly 10. The optical assembly 10 includes a bottom light enhancement film 11 and a top light enhancement film 12 disposed over the bottom light enhancement film 11. Conventionally, coat a liquid adhesive layer 13 on the bottom surface of the top light enhancement film 12, insert the prisms of the bottom light enhancement film 11 into the liquid adhesive layer 13 by embossing and subsequently perform a heat treatment process or a UV illumination process on the liquid adhesive layer 13 so that the liquid adhesive layer 13 proceeds to a crosslink reaction to form a solid film to finish the adhesion between the bottom light enhancement film 11 and the top light enhancement film 12. It is advantageous that the adhesive layer 13 in the liquid state guarantees that there is enough contact area between the liquid adhesive layer 13 and the prisms of the bottom light enhancement film 11 to provide the adhesive stability of the optical assembly 10. However, because the adhesive layer 13 is in the liquid phase before adhesion, it is easy to see obvious “wick phenomenon” (i.e. capillarity phenomenon) during adhesion so that it is not easy to control the contact area between the liquid adhesive layer 13 and the prisms of the bottom light enhancement film 11 and further the optical property after adhesion gets worse. The larger the contact area during adhesion is, the worse the optical gain (i.e. brightness) is.
There is also another way to finish adhesion. Coat a liquid adhesive layer 13 on the bottom surface of the top light enhancement film 12, perform the illumination process or the heat treatment process to make the liquid adhesive layer 13 proceed to a crosslink reaction to form a solid film, and then insert the prisms of the bottom light enhancement film 11 into the solid adhesive layer 13 by embossing to finish the adhesion between the bottom light enhancement film 11 and the top light enhancement film 12. It is advantageous that the liquid adhesive layer 13 after solidification do not have flowability so as to reduce “wick phenomenon”. However, because the liquid adhesive layer 13 is solidified first, most of the bonding between the prisms of the bottom light enhancement film 11 and the solid adhesive layer 13 is physical bonding, not chemical bonding, and therefore the adhesion force between the bottom light enhancement film 11 and the top light enhancement film 12 is usually weaker so that it is easy to have the peeling of the adhesion product in the subsequent trimming and assembling.
Accordingly, the present invention proposes an optical assembly and its manufacturing method to overcome the above-mentioned disadvantages.